Monro



R. MONRO LEAKPROOF GAS MASK Jan. 28; 1958 3 Sheets-Sheet 1 Filed March '7, 1955 ATTORNEY Jan. 28, 1958 a. MONRO 2,821,192

LEAKPROOF GAS MASK Filed March 7, 1955 3 Sheets-Sheet 2 Fig. 56

3 2 k FWYM Jan. 28, 1958 R. MONRO LEAKPROQF GAS MASK 3 Sheets-Shee'li 3 Filed March 7, 1955 fimdawh Monro A F W United States Patent LEAKPROOF GAS MASK Randolph Monro, Joppa, Md.

Application March 7, 1955, Serial No. 492,809

8 Claims. (Cl. 128141) (Granted under Title 35, U. S. Code (1952), sec. 266) The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment to me of any royalty thereon.

This invention relates to a leakproof gas mask embodying a hood covering substantially the entire head of the wearer and forming an exhalation chamber.

An object of this invention is to provide a gas mask which will effectively prevent leakage through the outlet valve and around the faceblank.

A further object is to provide a gas mask adapted to provide protection to the head and neck against vesicants or absorbable poisons.

A further object is to provide a hooded gas mask having lenses which are non-fogging and which otherwise provide good vision.

This application is a continuation-in-part of my applications, Serial No. 642,772 filed January 22, 1946 (now abandoned), and Serial No. 353,455 filed May 6, 1953, now Patent No. 2,800,901.

In the drawings, Fig. 1 is a back perspective view of one modification of my mask showing the hood partially removed.

Fig. 2 is a front perspective view of the modification of Fig. 1.

Fig. 3 is a view showing the hood in section on line 3-3 of Fig. 2 and showing the inner mask in elevation.

Fig. 4 is a front perspective view of another modification of a mask according to my invention.

Fig. 5 is a front perspective view of a third modification.

Fig. 6 is a section on line 66 of Fig. 5.

Fig. 7 is a view, partially in section, showing the mounting of the canister on the mask.

Fig. 8 is a section on line 8-8 of Fig. 7, with parts broken away.

Fig. 9 is a section taken through an eyepiece.

Fig. 10 is a front view of the inner mask, with parts broken away to show the flow of air.

During the past few decades, gas masks have undergone an extensive development. The standard models employed by the United States Army are formed with molded rubber facepieces which closely fit the face of the wearer. They are fitted with eyepieces, either one for each eye or a single member extending across both eyes, which are rigidly mounted in the facepiece. The molded facepiece and the rigidly mounted eyepieces hold the lenses in fixed position in front of the eye to provide good vision. For still better vision, the lenses are cylindrically curved. Such masks are provided with air purifying canisters through which air is inhaled and one-way outlet valves through which the air is exhaled.

In the standard models in use since 1942, a nose cup within the faceblank covers the mouth and nose. It communicates directly with the outlet valve and is provided with inlet valves which permit air from within the faceblank to enter the nose cup, but prevent reverse flow.

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Moist exhaled air thus is prevented from contacting the interior of the lenses, preventing fogging.

Such gas masks have proven highly successful as a protection against military gases of the type hitherto known in warfare. They are, however, not completely leak-proof. A slight leakage may occur around the faceblank. Also the inertia, though slight, of the outlet valve permits a slight leakage at that point. The development of gases having a reported toxicity far beyond that of the hitherto known military gases makes it essential to avoid even this slight leakage.

Gas masks have also been proposed in which the air is exhaled into a space within the mask, producing a super-atmospheric pressure for the purpose of preventing leakage. These proposed masks, however, are so constructed that the moist exhaled air is in contact with the inner surfaces of the lenses, causing fogging. Moreover, in those masks of this type which are formed as a hood covering the entire head, the lenses are not held firmly in a fixed position in front of the eyes.

I have devised a mask in which the air is discharged through a hood in which a slight super-atmospheric pressure is maintained, which mask also retains all the advantages of the standard models set out above. This I accomplish by combining with one of the highly perfected conventional type of masks a hood which covers the entire head and neck of the wearer and also covers the outlet valve of the mask. The hood is provided with openings which surround the air inlet connection as well as the eyepieces, and the margins of these openings are snugly joined to the mask.

The hood is also tightened about the neck of the wearer. Thus exhaled air builds up a super-atmospheric pressure within the hood, effectively preventing inward leakage around the faceblank of the mask or through the outlet valve, yet it never comes in contact with the inner surfaces of the lenses. Moreover, since the lenses are carried by the faceblank rather than by the flexible hood they are held fixedly before the eyes. By the use of the term tightened here and elsewhere in this specification, I do not intend to indicate that the fit is gastight. As will appear later, the air escapes around the neck of the wearer.

In the drawings, I have shown three modifications of the hood, one being shown in Figs. 1, 2, and 3, a second in Fig. 4 and a third in Figs. 5 and 6. The facepiece, as disclosed, is identical in all forms and the relation of the facepiece and hood is essentially the same. Referring to the modification of Figs. 1, 2, and 3, my mask includes a hood 1 and a facepiece 3, the latter being provided within an inlet connection 5, to which is in turn secured a canister 7. An air inlet valve may be provided either in the air inlet connection 5 or the canister 7, depending on the particular type of canister employed. Air is directed from the canister through the inlet connection and into the mask in a manner which will be described in more detail later in this specification.

Mounted on the facepiece is an outlet assembly 9 through which air is exhausted into the hood. A draw string 11 tightens the hood about the neck of the wearer. The individual adjusts the draw string to a point at which the hood ordinarily remains inflated but the air escapes at the desired rate and there is no undue discomfort. In general, the tightness maintained is much the same as that of an ordinary collar and necktie. The details of the facepiece and its relation to the hood will be described later.

Similarly, the modification of Fig. 4 includes the face piece 3 carrying the canister 7, together with hood 1t) having a draw string 12.

In the modification of Figs. 5 and 6, I employ a hood '0 d3 21 together with the facepiece 3, provided with air inlet connection 5, canister 7 and outlet assembly 9. A draw' string 31 tightens the hood about the neck of the wearer. The structure thus fardescribed is the sameas that of .the other modifications. The hood, however, is made in two.

parts, namely, an outer hood 33'an'd an inner hood 35' which are joined adjacent the neck portion by a seam 37. An air opening 38 is provided'intheinn'er hood and draw string 31 is mounted on the inner hood 35. Outlet assembly 9 discharges into the space between'the inner and outer hoods. the outer hood is provided with a small drainage hole '40 covered by a flap 42.

The facepiece 3, as shown inthe-drawings, iside'nti'cal in all three forms and is best shown in' Fig. 6'; It in-' cludes a 'faceblank-39 of molded rubber, closely conforming to, and covering substantially completely; the wearers face. The faceblank includescheek portion 41, a portion 43 covering the chin and lower jaw, and nose' protuberance 44. Eyepieces 45 (see Fig. 9) are firmly-mounted-in the facepiece. They include eyerings 47 which project ounwardly from the faceblank 39* andholdcylind'rically curved lenses. 49. While I-have shown-aseparateeyepiece for each eye, it will be understood that a single eyepiece extending across the entire. front of the faeeblank may be employed instead. The faceblank is formed,over a portion of. its area, oft two separated thicknesses-51 and 53, thereby forming a deflector tube which leadsfrom' the inlet connection to theinner surface .ofeach' eye piece (see Figs. 6, 7 and '10).

In the faceblank isv a. nose. cup 54 formedof fiexible, resilient rubber and covering the. mouth and nose. The upper portion is curved inwardly at.55 forming a seal across and around the nose while the'lower'portion 57 is held about the mouth by the faceblank. In the nose cup are two inlet valves 59 which permit the inwardflow of air but prevent outward flow. An outlet tube 61. leads from the nose cup 53 through the faceblank. tothe air outlet assembly 9 which latter is provided with a conventional one-way outlet valve (not shown).

A head harness 63 holds the faceblank in place.

The relationship of the hood and facepiecewill nowbe described. In the modification of Figs. 1, 2, and Band that of Figs. 5 and 6, the hood covers the entire facepiece except for the inlet connection and the eyepiece. The hood is formed with an opening to receive each of these elements and means are provided for tightening the edge of each opening about the element which it embraces. While there should be a snug fit at these points, gastight connections are unnecessary. The relationship of the hood to the air inlet connection 5 is shown in.-Fig. 7. The edge 65 of the opening is provided withha draw string .67 which tightens the hood about the. inlet con-. nection. When the double hood illustrated in Figs. 5 and 6 is used, the two hoods are joined together at thispoint by seam 69 surrounding the opening. Fig. 9 shows the relation of the hood to an eyepiece. Edge71 istightened by draw string 73 about eyering 47 '(this Fig. 9 shows only a single hood as in Figs. 1, 2, and 13). If a double hood is used, the inner and outer hoods would be joined as shown in Fig. 7. When the double hood is used, a similar structure tightens edge 75 of the opening in the inner hood about the air outlet. 7

In Fig. 4, I have shown a modified hood 10. Instead of having a separate opening for each eyering 47, this modification is provided with a single opening having an elastic edge 64 which fits over and beside the eyerings 47 and under the nose protuberance 44. The edge 64 is so formed, e. g, with an elastic insert, as to have a high degree of elasticity, so that it fits snugly against the face piece. The edge 66, which embraces the air inlet connection, is likewise formed with a high degree of elasticity, so that when in place it will embrace the air inlet connection, but can be stretched to pass over thecanister; This form of hood is advantageous in that the wearer Adjacent the lowest point on seam" 37,"

4'. can very easily put it on or take it off without removing the'mask: Moreover, the samehood may be-used either with the type of facepiece shown, having two eyepieces, or one having a single lens extending over both eyes. This hood may be either of the single type, shown in Figs. 1, 2, and 3, or the double type, shown in Figs. 5 and 6.

Preferably, the hood of. whatever specific form is provided with a self-contained pocket into which the hood may be folded, as described in' detail in application Serial No. 287,408, filed May 12, 1952,. byRaudolph Monro and Pearl E. Lackey.

When air-is inhaled; it flows inwardly through canister 7, in through inlet connection. 5 and along deflector tube 51, 53 to the inside surfaces of lenses 49." It then passes throughinlet'valves 59 into nose cup 53 andthence'to. the lungs. On exhaling, air passes from nose cup 53 through outlet tube 61 and outlet assembly 9 to the space within the hood, inflating the latter and. building up pressure. It then escapes through the snugbut' not gas .tight fit aroundthe'neckof'the'wearer; Since'the hood fits snugly at this point, asuperatmospheric pressure is maintained inside, preventing inward leakage; Air may also escape to-someextent about the eyepieces' and'air inlet connection: Itmayalsodeakout through needle holes or the like: Thusthe-=hoodneed not be absolutely gas tight. Even if,on-"inhaling, there is a'slight leakage inward'through'the outlet valves or:around the facepiece, this is so small compared to the -flow'of' air exhaled that a super-atmospheric pressure will normally be maintained. Furthermore, since an appreciable body of exhaled air is contained in the hood, any leakage ofair into the facepiece will be 'from that body-of air; The volume exhaled at each breath will be'far greater than any amount of outside air which might possibly gain entrance into the hood-. Hence, any air leaking into the facepiece will be uncontaminatedeven-if the pressure in the hood should dropto atmospheric :betweenbreaths.

In the form shown in Figs. Sand 6, airis exhaled into the space between the inner-andv outer hoods, first inflating. the .outer hood. Air then flows through open-- ing 38 into the inner hood, from which it finally escapes intthe'imanneridescribed above. This form of hood is intended to be worn in relatively cold weather. The presence :oiIthe double: hood "serves to maintain a body ofwarm. air,.protecting the wearer as. disclosed in my applicatiomSerial No; 353,455. Moreover, since the surfaceof theaonterhoodris. the. coldest area, moisture will:condense:thereonnand;v if .not .frozen, will eventually escape through drainage hole 40. Due to its small size, say 5 inch diameter; and therfactthat it iscovereduby flap 42', this holeiwill.not'iresultin' a-material loss of air pressure nor permit-"any substantial leakage of air into. the hood;

It will be noted that at no time, in any of my modifications, does the moistr'exhaled air come in contactwith the'inner surfacesof the: lenses so that no deposition ;-of moisture can occur-fromz that source. lenses areswept'by the fresh air flowing into themask. This removes any =m'oisture which may have evaporated from the eyes or skin and condensed on the'lenses.

The hood may; be formed ofany; substantiallygastight sheet material havingsuitable mechanical properties. Butyl'rubber-coated cloth i suitable, .particularly thin, butyl-rubber-impregnated nylon. The hood may also be impregnated withvesicant destroying material.

While I have described three embodiments of my invention in. detail,v it will. be understood that various changes are: possible. I, therefore, wish my invention to be restricted solelyby the scope of. theappendedclaims.:

I claim:

1. ln..a gas'mask, afacepiece assembly comprising a faceblank, at least one eyepiece mounted on. said. face blank, a nose. cup within said faceblank, said nose cup, including atleastone inlet valve,,means forintroducing purifiedaair.into.said.mask and comprising an. inlet cott- Furthermore, the

nection mounted on said faceblank, an air outlet tube leading from said nose cup through said faceblank, an air outlet valve in said air outlet tube, and means for securing said faceblank to the face of a wearer; a substantially gas-impermeable hood constructed and arranged to cover said facepiece, said air outlet valve and the head and neck of the wearer, said hood comprising openings receiving said eyepiece and said air inlet connection, and means retaining the edges of each of said openings in contact with said facepiece, and wherein each said eyepiece comprises an eyering projecting outwardly from said faceblank and said means for retaining the edges of each of said openings in contact with said facepiece comprises means for tightening the edges of said openings about each said eyering and said air inlet connection.

2. In a gas mask, a facepiece assembly comprising a faceblank, at least one eyepiece mounted on said faceblank, a nose cup within said faceblank, said nose cup including at least one inlet valve, means for introducing purified air into said mask and comprising an inlet connection mounted on said faceblank, an air outlet tube leading from said nose cup through said faceblank, an air outlet valve in said air outlet tube, and means for securing said faceblank to the face of a wearer; a substantially gas-impermeable hood constructed and arranged to cover said facepiece, said air outlet valve and the head and neck of the wearer, said hood comprising openings receivings said eyepiece and said air inlet connection, and means retaining the edges of each of said openings in contact with said facepiece, and wherein each said eyepiece comprises an eyering projecting outwardly from said faceblank, said faceblank includes a nose projection, and said hood comprises a first opening receiving each said eyepiece and said nose projection and a second opening receiving said air inlet connection, and each of said openings is surrounded by an elastic edge portion.

3. A gas mask as defined in claim 1 wherein said tightening means comprises a draw string about each opening.

4. In a gas mask, a facepiece assembly comprising a faceblank, at least one eyepiece mounted on said faceblank, a nose cup within said faceblank, said nose cup including at least one inlet valve, means for introducing purified air into said mask and comprising an inlet connection mounted on said faceblank, an air outlet tube leading from said nose cup through said faceblank, an air outlet valve in said air outlet tube, and means for securing said faceblank to the face of a wearer; a substantially gas-impermeable hood constructed and arranged to cover said facepiece, said air outlet valve and the head and neck of the wearer, said hood comprising openings receiving said eyepiece and said air inlet connection, and means retaining the edges of each of said openings in contact with said facepiece, and wherein said hood comprises an outer hood and an inner hood, means joining said outer hood and inner hood adjacent the neck of the wearer and about each of said aforementioned openings, an opening in said inner hood receiving said outlet tube, means securing said inner hood to said facepiece adjacent said outlet tube, and an air opening in said inner hood spaced from said outlet valve.

5. In a gas mask, a facepiece assembly comprising a faceblank, at least one eyepiece mounted on said faceblank, a nose cup within said faceblank, said nose cup including at least one inlet valve, means for introducing purified air into said mask and comprising an inlet connection mounted on said faceblank, a deflector tube leading from said air inlet connection to a point adjacent said eyepiece which is adapted to circulate purified air over at least one eyepiece to prevent fogging an air outlet tube leading from said nose cup through said faceblank, an air outlet valve in said air outlet tube, and means for securing said faceblank to the face of a wearer; a substantially gas-impermeable hood constructed and arranged to cover said facepiece, said air outlet valve and the head and neck of the wearer, said hood comprising openings receiving said eyepiece and said air inlet connection, and means retaining the edges of each of said openings in contact with said facepiece.

6. In a gas mask, a facepiece comprising a faceblank, which faceblank includes at least one inlet valve and a transparent eyepiece means mounted therein, means for introducing purified air into said mask, which means further comprises an air inlet connection mounted on said faceblank adapted to admit purified air from the enviroment of the faceblank, remote from the wearer, through the faceblank to the wearer, an air outlet means through said faceblank and constructed so as to include an air outlet valve such that the exhausted air will not fog the transparent eyepiece means, means for securing said faceblank to the wearer; a substantially gas-impermeable hood constructed and arranged to cover said facepiece, siad air outlet means and the head and neck of the wearer, said hood comprising openings adapted to receive said transparent eyepiece means and said purified air introducing means and means retaining the edges of each of said openings in contact with said facepiece.

7. In a gas mask, a facepiece comprising a molded rubber faceblank closely conforming to the face of a wearer and inclosing substantially the entire face, a nose cup within said faceblank, at least one inlet valve in said nose cup constructed and arranged to permit air to flow from the interior of said facepiece into said nose cup while preventing reverse flow, an air outlet tube leading from said nose cup through said faceblank, an air outlet valve in said air outlet tube, at least one eyepiece rigidly mounted in said faceblank, each said eyepiece comprising an eyering projecting outwardly from said faceblank and a lens mounted in said eyering, means for introducing purified air into said faceblank and comprising an air inlet connection mounted on said faceblank, a deflector tube leading from said connection to a point adjacent the inner surface of each said eyepiece, and means for securing said faceblank to the face of a wearer; a substantially gas-impermeable hood constructed and arranged to cover said facepiece, said air outlet valve and the head and neck of the wearer, said hood comprising openings receiving each said eyepiece and said air inlet connection, means for tightening the edges of said openings about each said eyepiece and said air inlet connection and means for tightening said hood about the neck of the wearer.

8. A gas mask as defined in claim 7 wherein said hood comprises an outer hood and an inner hood, means joining said outer hood and inner hood adjacent the neck of the wearer and about each of said aforementioned openings, an opening in said inner hood receiving said outlet tube, means securing said inner hood to said facepiece adjacent said outlet tube and an air opening in said inner hood spaced from said outlet valve.

References Cited in the file of this patent UNITED STATES PATENTS 1,929,343 Belloni Oct, 3, 1933 2,446,530 De Gratia et al Aug. 10, 1948 2,448,021 De Gratia Aug. 31, 1948 FOREIGN PATENTS 539,933 Great Britain Sept. 30, 1941 

